Intrepid modder builds an M4-powered 4K iMac G3 with 3D-printed parts — guts 90s all-in-one and replaces internals with a Mac mini and an OLED screen

M4 iMac G3
(Image credit: Zac Builds/YouTube)

YouTube and tinkerer Zac Builds has built an M4 iMac using an old iMac G3. Apple released the iMac G3 in 1998, and the device is often seen as one of the things that helped the company stave off bankruptcy in the ‘90s. Aside from that, it had a unique design and was one of its first devices to feature the “i” prefix, making it one of the most iconic Apple products. We can see in the YouTube video that Zac Builds started with an iMac G3 (although not the Bondi Blue version), which he then disassembled. After taking everything apart, he then replaced all the components with modern parts to turn it into an Apple computer you can comfortably use today.

He started by removing all the screws and covers, gingerly dismantling the old computer so he could reuse its frame and outer shell. Unfortunately, time has taken its toll on some of the iMac G3’s parts — its speakers are completely gone, and the CRT screen’s bezel crumbled as soon as Zac touched it. Once he completed deconstructing the all-in-one, all that was left was the main motherboard frame and the white translucent case, which serve as the base of the build.

I built a MODERN iMac G3... - YouTube I built a MODERN iMac G3... - YouTube
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From here, Zac first started by 3D printing the parts needed to reinforce the shell of the old iMac, as many of the components that he took out earlier supplied some of the structural integrity of the computer. With that in place, he vigorously shook the computer to see if it would come apart, and it seems that his additions ensured that none of its parts were going anywhere. He then reused the G3’s power supply, carefully desoldering it from the original motherboard and then mounting it on a spacer to deliver power to the Mac mini that will serve as the brains of this build. This was a relatively simple operation; the original power supply simply worked like a power strip, delivering 120 volts to the internal components of the iMac.

Outer shell and motherboard frame for the iMac G3

(Image credit: Zac Builds/YouTube)

The next step was to install the Mac mini inside the shell of the old G3. Instead of disassembling the modern mini PC, he just mounted it directly inside, trimmed its power supply to fit neatly inside the AIO, and then created a modular power system that will power all the components within the M4 iMac G3 through the original power cable. Since Apple charges an arm and a leg for extra storage, Zac added a dock with a built-in SSD slot to expand the computer’s capacity without paying hundreds of dollars for it.

mounting the M4 Mac mini inside the case of the iMac G3

(Image credit: Zac Builds/YouTube)

With the brains of the build in place, he then added a pair of new speakers mounted on 3D printed enclosures to replace the old broken ones. They were then connected to a 200-watt digital amplifier, as the Mac mini’s 3.5 mm audio output is not powerful enough to drive them natively. He then installed it in such a way that the adjustment knobs are still easily accessible through the old RAM access door of the G3.

Of course, Zac had to 3D-print brand-new ports as he could not reach the Mac mini inside the case without removing the screen. He added a Thunderbolt port, a USB-C port, a couple of USB-A ports, and an Ethernet port, ensuring that he still had some of the functionality of the original computer despite being placed in the case. There’s no 3.5mm jack, though, as it’s already in use by the built-in speakers he added to the iMac. So, if he wants personal audio, he’ll have to stick with one of the best wireless gaming headsets.

cable spaghetti in the M4 iMac G3

(Image credit: Zac Builds/YouTube)

With everything in place, the YouTuber installed a 14-inch 4K portable monitor with a custom 3D printed interposer that fills in the gap between the rounded front face and the flat display. And with that, we now have a fully working M4 iMac G3. This computer gives anyone who’s ever used the G3 back in the late ‘90s and early 2000s a hit of nostalgia, while remaining usable in modern computing. You can also catch a glimpse of the Mac mini powering the entire thing at the back, along with the clutter of wires that connect it all together. It probably would’ve been nicer if Zac cable-managed the internal spaghetti, but that’s just a minor detail in this certainly interesting build.

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Jowi Morales
Contributing Writer

Jowi Morales is a tech enthusiast with years of experience working in the industry. He’s been writing with several tech publications since 2021, where he’s been interested in tech hardware and consumer electronics.